The disclosure relates to an onboard electrical system and to a method for operating an onboard electrical system for a motor vehicle.
In addition, a motor vehicle having such an onboard electrical system is specified, and also a battery management system and a computer program that are set up to carry out the methods described.
In motor vehicles having an internal combustion engine, an onboard electrical system that is operated at 12 V as standard is provided for supplying power to the electric starter for the internal combustion engine and to further electrical apparatuses of the motor vehicle. When starting the internal combustion engine, the onboard electrical system is used to provide a voltage from a starter battery for a starter that starts the internal combustion engine when a switch is closed, for example by an appropriate starter signal. Once the internal combustion engine has been started, it drives an electrical generator that then produces a voltage of approximately 12 V and provides it for the various electrical loads in the vehicle via the onboard electrical system. In so doing, the electrical generator also recharges the starter battery loaded by the starting process. When the battery is charged via the onboard electrical system, the actual voltage may also be above the rated voltage, e.g. at 14 V or at 14.4 V. The onboard electrical system at a voltage of 12 V or 14 V is also referred to as a low voltage onboard electrical system within the context of the present disclosure.
It is known practice to use a further onboard electrical system having a rated voltage of 48 V in electric and hybrid vehicles, said system also being referred to as a high voltage onboard electrical system within the context of the disclosure.